Ensemble responses of auditory midbrain neurons in the cat to speech stimuli at different signal-to-noise ratios
dc.contributor.author | Anu Sabu | |
dc.contributor.author | Dexter Irvine | |
dc.contributor.author | David B Grayden | |
dc.contributor.author | James Fallon | |
dc.date.accessioned | 2025-02-13T00:41:17Z | |
dc.date.available | 2025-02-13T00:41:17Z | |
dc.date.issued | 2024-12-03 | |
dc.description.abstract | Originally reserved for those who are profoundly deaf, cochlear implantation is now common for people with partial hearing loss, particularly when combined with a hearing aid. This combined intervention enhances speech comprehension and sound quality when compared to electrical stimulation alone, particularly in noisy environments, but the physiological basis for the benefits is not well understood. Our long-term aim is to elucidate the underlying physiological mechanisms of this improvement, and as a first step in this process, we have investigated in normal hearing cats, the degree to which the patterns of neural activity evoked in the inferior colliculus (IC) by speech sounds in various levels of noise allows discrimination between those sounds. Neuronal responses were recorded simultaneously from 32 sites across the tonotopic axis of the IC in anaesthetised normal hearing cats (n = 7). Speech sounds were presented at 20, 40 and 60 dB SPL in quiet and with increasing levels of additive noise (signal-to-noise ratios (SNRs) –20, –15, –10, –5, 0, +5, +10, +15, +20 dB). Neural discrimination was assessed using a Euclidean measure of distance between neural responses, resulting in a function reflecting speech sound differentiation across various SNRs. Responses of IC neurons reliably encoded the speech stimuli when presented in quiet, with optimal performance when an analysis bin-width of 5–10 ms was used. Discrimination thresholds did not depend on stimulus level and were best for shorter analysis binwidths. This study sheds light on how the auditory midbrain represents speech sounds and provides baseline data with which responses to electro-acoustic speech sounds in partially deafened animals can be compared. | |
dc.description.sponsorship | This research was supported by the Australian Research Council’s Discovery Project Grant (DP210103791). We would like to acknowledge the Passe and Williams Foundation for the Junior Fellowship Grant. The Bionics Institute also acknowledges the support they receive from the Victorian Government through its Operational Infrastructural Support Program. We would like to thank the Engineering Team and the Animal Research Team at Bionics Institute for their help with electrophysiological recordings and animal maintenance. | |
dc.identifier.citation | Sabu A, Irvine D, Grayden DB, Fallon J. Ensemble responses of auditory midbrain neurons in the cat to speech stimuli at different signal-to-noise ratios. Hear Res. 2025 Feb;456:109163. doi: 10.1016/j.heares.2024.109163. Epub 2024 Dec 3. PMID: 39657280. | |
dc.identifier.uri | https://repository.bionicsinstitute.org/handle/123456789/469 | |
dc.publisher | Hearing Research | |
dc.title | Ensemble responses of auditory midbrain neurons in the cat to speech stimuli at different signal-to-noise ratios | |
dc.type | Article |